Approximately 50% of all cancer patients will receive radiation therapy (RT) during the course of their illness. Although radiation damages both normal cells as well as cancer cells, the goal of RT is to maximize the radiation dose to abnormal cancer cells while minimizing exposure to normal cells. Further indications of RT include combination strategies with other treatment modalities such as surgery, chemotherapy or immunotherapy. If used before surgery (neoadjuvant therapy), radiation will aim to shrink the tumor. If used after surgery (adjuvant therapy), radiation will destroy microscopic tumor cells that may have been left behind (Baskar et al., 2012).
Radiotherapy is used for curative treatment and palliative treatment of solid tumors.
Curative treatment in early-stage local tumor or recurrent cancer
RT can cure cancer, prevent it from returning, or stop or slow its growth by the following treatments:
- Radical treatment;
- Before surgery, to shrink the size of the cancer so it can be removed by surgery and be less likely to return: preoperative or neoadjuvant treatment;
- During surgery, so that it goes straight to the cancer without passing through the skin. RT used in this way is called intraoperative radiation. With this technique, nearby normal tissues can be more easily protected from radiation: this treatment modality is referred to as intraoperative treatment;
- After surgery to kill any cancer cells that remain: referred to as adjuvant treatment.
Palliative treatment for advanced cancer
External beam radiation may shrink tumors to treat pain and other problems caused by the tumor, such as trouble breathing or loss of bowel and bladder control.